The Macintosh IIcx was introduced by Apple Computer in 1989, half a year after the introduction of the Macintosh IIx. The IIcx resembled the IIx to a great extent and provided the same performance, but was quieter (due to its quieter fan on a smaller power supply) than its predecessor. Reducing the number of NuBus slots from 6 to 3 also made the machine much more compact. The new case, Apple's first to be designed to operate in either horizontal or vertical orientation, remained in use for its successors the IIci and Quadra 700. The idea for vertical orientation, one of the first minitower cases, was suggested by Apple CEO John Sculley, who was running out of space on his desk,[1] despite the fact that the new layout actually took more space once the monitor was taken into account. The model was designated IIcx for compact (echoing the earlier Apple IIc compact model in the Apple II series), and the x was Apple's designation for the 68030 processor.

Users liked the Mac IIcx in part because its components and parts (such as RAM, NuBus slots, and power supply) snapped into place inside the case without the need for screws. There was one central safety screw that tied the assembly together though it was often not reinstalled if ever removed. At the IIcx's introduction, Jean-Louis Gassee demonstrated the IIcx's modular design by assembling one from parts in front of the audience [2] This made it less expensive to build, easier to repair, and earned it heavy praise and a warm reception amongst the Mac community.

This model was superseded by the Macintosh IIci which used the same case.